Wikipedia:Reference desk archive/Science/2006 July 13

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I usually use a mouse with a scroll wheel to navigate firefox. This is especially useful, as clicking the scroll wheel on a tab closes it, while clicking it on a link opens the link in a new tab. However, I have been unsuccessful at getting this function to work with that button on the laptop that is roughly analogous to the scroll wheel on a mouse (is there a name for that button?). Does anybody know how to implement these features with a laptop mouse, or is this impossible? JianLi 00:23, 13 July 2006 (UTC)

unless the scroll button is working in Firefox but performing a different function, this is probably a hardware issue or a global (OS level) issue. Does the scroll wheel work in other apps? Does it do anything in Firefox? (sometimes it's set to go back or forward or something like that)

You forgot to say what OS you're using. In Linux, you have to make sure you're using the right driver. The regular PS/2 mouse driver will work with a touchpad, but it won't support the extra things like scrolling. I use the Synaptics driver on my Thinkpad and it works great. —Keenan Pepper 20:34, 13 July 2006 (UTC)

Yeah, middle click seems right. And I'm using Windows. So my question is basically, how do you get "middle click" to work on a laptop (say, a ThinkPad) running Windows? JianLi 22:26, 18 July 2006 (UTC)

Sometimes you can change the mouse settings in the control panel (in Windows XP) so that clicking both buttons sends a "middle click" event.

What makes the color red susceptible to fast fadinmg in the sunlight? What is the molecular structure of the red pigment, and how does the sun affect gthat pigment to made the color fade. Does it change the red molecule? If so, what change is made? The red ink printed on paper seems to be very fast in fading -- does this depend on the quality of the ink? The red color in a Polaroid photo seems to resist fading. I've seen street signs on which all of the red has completely faded.

Just what is happening to the red?

it depends on the type of red dye. the reason the dye is coloured in the first place is that the dye has been chmeically designed in such a way as to selectively absorb certain wavelengths of light, leaving only the red to be transmitted or reflected. the energy gained by the dye molecule from the light has to be gotten rid off, normally the molcule can lose the energy through vibration or rotatation, but sometimes that energy can go to causing a chemical reaction instead. this reaction changes the structure of the dye, so it no longer absorbs the right wavelengths of light. on the bulk scale, you slowly observe a fading red colour. Xcomradex 00:59, 13 July 2006 (UTC)

The photons that things that reflect red absorb (i.e., not red) are of higher energy than the photons that things that aren't red absorb (i.e., red). In particular, if we assume that dyes have a relatively large bandwidth and only gradual changes in absorptivity, things that are blue should reflect some violet and UV, and things that are red should reflect some IR but absorb lots of UV. And UV photons are typically energetic enough to dissociate organic molecules (and others; see ozone). So that's why (if I understand correctly) red is preferentially destroyed. Xcomradex's answer is of course correct in terms of how any dye is destroyed, ever. --Tardis 15:49, 13 July 2006 (UTC)

Go to the wikipedia article on anemia, and scroll down to the section called "Signs and Symptoms". You could also look at Iron Deficiency, because that is often a cause, and therefore the symptoms can go hand in hand. My favorite is pagophagia. --Bmk 02:26, 13 July 2006 (UTC)

I'd answer, but I don't have the energy at the moment. StuRat 15:49, 13 July 2006 (UTC)

Signs and symptoms Anemia goes undetected in many people, and symptoms can be vague. Most commonly, people with anemia report a feeling of weakness or fatigue. People with more severe anemia sometimes report shortness of breath. Very severe anemia prompts the body to compensate by markedly increasing cardiac output, leading to palpitations and sweatiness; this process can lead to heart failure in elderly people.

Pallor (pale skin and mucosal linings) is only notable in cases of severe anemia, and is therefore not a reliable sign.

Seems like a homework question. From Wikipedia: "Virtual Libraries are a libraries that consist only of resources available in a digital format, which can be accessed locally - stored on a hard disk - or through computer networks - public or private." Or just follow the link the person above provided. --Proficient 04:05, 14 July 2006 (UTC)

i AM FROM iNDIA.WE GET LOW FAT MILK FROM THE DIARIES. THE MILK FROM DAIRIES ARE NOT ORGANIC.I GET GOOD FRESH MILK BUT IT CONTAINS 5.5% FAT. WILL IT BE POSSIBLE FOR ME TO REDUCE THE FAT CONTENT AT HOME?

If your milk is not homogenized, you can let it sit for a day or two and skim off the fat. But if it is, you would need a centrifuge to seperate the milkfat from the rest of the milk. Crazywolf 06:20, 13 July 2006 (UTC)

Repeated freezing may also cause the fat to clump together, but be sure to pour some off and crack the top, to allow for expansion. StuRat 15:39, 13 July 2006 (UTC)

Also, I assume from your question that lowfat milk is not available in your part of India. This used to be the case in the rest of the world, too, until the health risks of a high fat diet became apparent. Initially, lowfat milk was cheaper than whole milk, as it was left over when cream was produced for ice cream, etc. Later, as demand for lowfat milk increased, the price became the same as for whole milk. StuRat 15:44, 13 July 2006 (UTC)

I believe that what they are saying is that low fat milk is available, but not low-fat organic milk. As far as that goes, I would say that low fat milk is better for you than high fat organic milk.

You might look into whether you have access to any alternative food stores to the generic dairies.

It is also possible to buy powdered milk, which has a long shelf life, which you then mix with water (preferably clean fresh boiled water) to get the drinkable milk. I guess you could use excess water it down.

Some places, Goat's Milk is a suitable substitute for Cow's Milk. May I ask a delicate question about Reincarnation? It is my understanding that one of the primary religions of the people of India have people being reincarnated as various different animals depending on how good we are in this life, in which a Cow is at the top of the ladder. Within that religion, is it inappropriate to be consuming food products that came from that animal? User:AlMac|(talk) 02:36, 14 July 2006 (UTC)

No, absolutely not. Of course, there is a prohibition against eating the flesh of a cow (since you'd have to kill the cow to do it) but other food products (milk, yoghurt, ghee) are not only not prohibited, they are used in religious ritual. (And of course, there are the famous milk-drinking statues.....) - Nunh-huh 08:26, 14 July 2006 (UTC)

A decrease in blood pressure triggers a barorecptor reflex that leads to increased ventalation. What is the possible advantage of this reflex?--69.180.243.11 04:04, 13 July 2006 (UTC)

This sounds suspiciously like a homework question... IANAD and have never done any real anatomy so this is an educated guess (confirmation would be good). I'd say blood pressure decrease may indicate less blood bein circulated. Hyperventilation increases oxygen supply to the bloodstream. Therefore, hyperventilation with blood pressure drop would ensure that the amount of oxygen reaching the brain and other vital organs wouldn't decline to dangerous levels. Grutness...wha? 08:40, 13 July 2006 (UTC)

right on. Low blood pressure, caused by many things -- dialated vasculature, blood loss, etc. -- means the brain may not be getting enough oxygen. Baroreceptors trigger a large hormone-mediated response which does a lot of things, including increasing ventilation, which, in turn, bumps up the oxygen level in the blood. That's the quick and dirty.

In India, construction industry is in boom but it is inhibted by low quality and irregular supply. I have done some work on the subject and find that low price is a great price advantage brick has gives it cpmpetitive edge over other substitute products. Increasing demand for agricultural land and general ecological conerns including conservation of sub soil water resources have led to initiation of policies, which seek to restrict use of top soil for non agricultural use. There is also the issue of utilizing ash generated by coal and lignite based thermal power stations in India. In this background there is need for a cost effective technology which has advanatage of low energy consumption, low material consumption, low CO2 emmission and finally and very importantly low initial capital outlay. Can I ask your research and reference to give me access to information on manufacturers of hollow clay block machine munufacturers / suppliers ( new and old.) Any further clarification can be referred to me.

Interstate Brick is a company that manufactures hollow bricks, check the structural bricks section. These bricks have large rectangular holes taken out of them, similar to concrete cinderblocks. Higgins Brick is a company that sells cored bricks, which are bricks with cylindrical holes in them. I wasn't sure which of those you wanted. I found these two companies from the list of clay brick manufacturers at WSCPA manufacturers and I am sure you can find more companies that have the information you need there. Crazywolf 06:01, 13 July 2006 (UTC)

I would say circular holes are best, as they facilitate quicker drying and baking, but don't lead to stress concentrations, which potentially cause fractures, like square holes would. Also, during construction, properly aligned holes can allow for either permanent or temporary poles to be run through the bricks, to hold them in place while the mortar dries. These could also be useful for running wires in a brick wall. StuRat 15:33, 13 July 2006 (UTC)

As an alternative, you could look at so-called earthships (weird name). Cheap material (possibly free), prevents CO2 emissions by burning cartyres. Just labour-intensive, but in India that is probably not the biggest problem. Als the advantage of heat preservation doesn't really help in India, although the article suggests that a 'wrong' design helps lose the heat. DirkvdM 09:25, 14 July 2006 (UTC)

A friend of mine had a movie in his computer, which was playing fine. So I got it on a cd-rw, but on my computer, there are various portions where the sound "runs" ahead of the video, and especially, towards the end of the movie, the sound runs 15-20 minutes ahead of the video. But on his computer there is no such problem. So what is happening? Any solutions to solve this? Thank You---Nikhilthemacho.

15–20 minutes? That sounds like more than a simple A/V synch issue to me. How exactly does it get that far off? Is the sound higher pitched than it should be? Does it gradually shift out of synch or does the audio ever abruptly skip ahead, or the video pause while the audio continues? Also, it's difficult to help unless you say what OS and video player you're using, what format the video is, things like that. —Keenan Pepper 20:41, 13 July 2006 (UTC)

Hello, does anyone have a link or know of websites which have the map of the whole world in a single image file. There are millions of websites showing maps of regions, but I couldnt find one as per my requirements. And I wish the image file should have large dimensions so that the clarity is also of acceptable limits. Thank You.

Thank you for your links, but i would like to have maps which are "political" in nature, i.e. show the names of all countries, and boundaries.(I think they are called political maps).And the map should be clear, because many maps are there, but they are too cluttered.

Note that a single map of the entire Earth will have major distortions, since the Earth is a sphere, and a sphere can't be flattened into a plane without distortions. This is why a series of maps is typically used instead. Antarctica particularly is messed up badly by most maps of the Earth. StuRat 15:24, 13 July 2006 (UTC)

The industrial float glass process was invented in the 19th century and put to commercial use in the 20th. So far so good. But it would be surprising if the basic idea of floating molten glass on molten metal really was that recent. So when is the float glass principle first known to have been used, or experimented with?

let's think. A wine glass . . . won't hold up a woman, no matter what shoes she is wearing. Bullet-proof glass . . . will. Let's have a little more detail about what kind of glass you're thinking of.

glass used to make glass slippers... i dunno wat glass b cause im supposed to find outmif cinderella can dance in glass slippers ... and answer it with some proof... can u pls help??

Somebody asked this question a few months ago. It's not easy to dance in any sort of slippers, and certainly not glass ones. If Cinderella slipped she could suffer some very nasty cuts to her feet. If you're planning a pantomime, get some polythene or acrylic ones made instead.--Shantavira 13:19, 13 July 2006 (UTC)

That very much depends on what kind of glass. That question can barely have a practical answer. --Proficient 04:10, 14 July 2006 (UTC)

Is it possible to focus all incoming raiation on some black material so that all the photons is converted to heat which can then be converted to energy?

Light energy can be focused pretty well with a Lens (optics). Practical application and example: burning ants. In theory this would work as you said, and some people do this, as in Solar cooker. I'm not sure what you mean by "convert heat to energy" as heat is a form of energy. If you mean electricity, you could cook some water, let it boil, and turn a turbine, but it's a whole lot more efficient to create electricity directly with a Solar cell, a brilliant little device that allows light to push electons. Moving electrons is, after all, electric current.

I think it depends on how you measure efficiency. Wikipedia's article on solar panels lists average efficiency at 12% and you also have to consider the considerable cost of the solar panel with its use of semiconductor materials. Something like a solar power tower focuses sunlight to a central point where it heats molten salt and uses that as the energy storage medium to be later used to convert water to steam. I'm sure lots of energy is wasted, but I would expect an energy/cost payback to be faster with this technology as it is overall much simpler if you count the infrstructure to produce it.

Also note that focusing light on a single point is quite dangerous, as anyone getting in the way can be blinded or burnt. StuRat 15:07, 13 July 2006 (UTC)

I meant converting all sort of incoming photons to heat energy,so that the fixed radiated wavelength is fully converted to electricity..

There are some errors in your assumption. Heat has multiple wavelengths (when it becomes infrared radiation). Besides, I'm not aware of anything like a photoelectric cell that works on infrared wavelengths. Heat energy therefore can not be converted into electricity with 100% efficiency. In fact, the usual method, a steam turbine, has a fairly low efficiency. StuRat 21:57, 14 July 2006 (UTC)

how about having two theoretical prefect black bodies,first for general photon radiation,second one for the many heat wavelenghts and then an optical filter to allow only required wavelength to pass,reflecting the rest back?

We know from maxwells equations for time varying that Div X H = J + ?D/?t and Div X E = -?B/?t....."?" stands for del,partial differentiation operator.But in first equation J = dI/dS or current density stands for the rate of change of charge q.So should not there be an analogous quantity in the second equation which stands for magnetic dipoles density applicable only to conductors say M=?m/?s or magnetic dipoles per unit area cross section?because guess first equation can be viewed with q in mind in the similar manner..

q stands for electric charge, or electric monopole charge. There are no magnetic monopoles found as yet. If you'd ever find one, publish an article and you'll be famous on the spot. Here is some more information. Greets, David 12:13, 13 July 2006 (UTC)

There may be no magnetic monopoles,but how about a single unit charge moving about a point that constitutes a unit magnetic field?

Can Anybody tell me the Amount of Pressure Glass can Hold... Sorry but i cant seem to be able to find anything on the web... Can sum1 pls help me??

It isn't clear what measure you are looking for. The thicker the glass, the more pressure it can hold; construction techniques will also be relevant, and the type of glass. I can't see that there is an upper limit. Notinasnaid 11:01, 13 July 2006 (UTC)

The shape of the glass and type of pressure are also critical. For example, a glass sphere (like a marble), could withstand huge levels of air pressure. StuRat 15:02, 13 July 2006 (UTC)

Another exampler: A teardrop shaped piece of glass can withstand hammer blows on the thick end but will shatter if the tail end is scratched. Rmhermen 18:08, 13 July 2006 (UTC)

Criss Angel could somehow levitates and "travel" accross a building. Eye witnesses are available beneath the gap between the buildings and both on the buildings. How could it be done? Thanks! See Video

well, his feet aren't moving, and he seems to be surrounded by blurry matte lines, I think it's magic--152.163.100.74 14:31, 13 July 2006 (UTC)

The simplest explanation is that the witnesses are shills, paid to say they see something that they really don't. StuRat 14:55, 13 July 2006 (UTC)

Saw the same thing with C3P0, and there were thousands of Ewoks there to corroborate :) --Bmk 15:32, 13 July 2006 (UTC)

I would hope it's something more than just shills and post processing. If that's the case, then it's just boring TV. I'd like to know the mechanics of the trick, but apparently that can never be discussed. —Bradley 17:33, 13 July 2006 (UTC)

The mechanics of the trick looks a lot like standing on a green screen, or powerful magnetic space monkeys, that would be my second guess--64.12.116.74 17:34, 13 July 2006 (UTC)

How many carbon-fiber spiderweb strands does it take to lift 200lbs? And would a big cluster of transparent balloons be visible if it was at the end of a 1000ft tether?--Wjbeaty 20:30, 13 July 2006 (UTC)

THat's nothing. I've seen David Copperfield levitate across the Grand Canyon. Try to figure out how he could do it without camera tricks or post production editing. There's usually a very easy way to do something seemingly impossible. Just think a little outside the box. - Mgm|(talk) 23:12, 13 July 2006 (UTC)

Unless of course he did it by camera tricks and post production editing. Then there probably won't be a vert easy way to do it. --Crazywolf 02:07, 14 July 2006 (UTC)

When there is a logical scientific explanation for something,

(or even an explanation we might not know enough science to evaluate),

Larry Niven wrote a delightvul "The Magic Goes Away" in which he theorized that magic was a non-renewable resource. If there is any validity in his theory, then this might explain stuff in history, such as Dragons that we have a hard time explaining scientifically today. User:AlMac|(talk) 02:45, 14 July 2006 (UTC)

A camera trick goes a long way. --Proficient 04:14, 14 July 2006 (UTC)

If all the stuff that people have been doing for years is REALLY bad for you, then how come we're not all dead? What are the real chances that this shit will actually kill you? small i bet--Crbbydemds 14:17, 13 July 2006 (UTC)

Some of those aren't very serious risks, like lead-based paints, while others, like "germs" do kill millions and could kill billions if we didn't take actions to prevent it. The main reason for the increase in life expectancy in the last few centuries is the widespread use of water purification systems to remove or kill "germs" in the water. Without this, people end up drinking water contaminated by raw sewage and dying from whatever the last person had who defecated into the water. One of the silliest concerns is mercury in thermometers, which, unlike methyl mercury, is quite stable and safe. Some environmentalists would have us treat it like plutonium, however. StuRat 14:43, 13 July 2006 (UTC)

Looking at only the risks of "dying" is quite narrow minded. The hazards you listed--and many, many others--don't always terminate "life" but more often do reduce "quality of life". For example, abosorbing a small quantity of lead in your bloodstream is unlikely to kill you but, above a specified threashold, can make you life less enjoyable. Therefore, if your life is nothing more than staying alive, then indeed you don't need to worry about most of these hazards. But if enjoyment comes into play, than start pay attention.--JLdesAlpins 15:23, 13 July 2006 (UTC)

I'm not sure why you listed STDs on your list. There's no question that AIDS is bad for you...you don't doubt that do you? And alcohol during pregnancy can do some nasty stuff - see fetal alcohol syndrome. Do you doubt the harmfulness of germs in general to human health? I'm not sure how to start. Perhaps you could read about smallpox. Just one example of some nasty microbes. Another horrible horrible way to die is from ebola. --Bmk!

Don't forget Fetal Alcohol Syndrome. The placenta is a marvel of protection but it's no match for a boozehound mother, and babies born to substance abusing mothers lead very diminished lives.

I didn't forget :) read my post again - also it's nice to add a signature - type four tildes (~) to add a signature and a date. --Bmk 18:35, 13 July 2006 (UTC)

Lead paint causes a large number of problems, particularly in young children, even though it doesn't seem to be a major cause of death. Second hand smoke is a factor in many deaths. Germs such as bacteria and viruses cause many diseases, many of which are deadly, although we now have weapons, including vaccines and antibiotics, against many of those. I don't know what you mean by baby boosters. Alchohol during pregnancy often causes serious conditions in the baby, including fetal alcohol syndrome and fetal alcohol effect. You're unusual if you have never met anyone suffering from those. Sexually transmitted diseases are sometimes curable (such as gonorrhea) but often not (such as AIDS, which is deadly). And we do see large numbers of people dying of AIDS, especially in Africa -- so many that it is affecting population demographics. Why are we not all dead? Because first, each of these factors carries only a risk of illness or death, not a guarantee, and second, many people avoid some or all of these things insofar as it is possible. --Ginkgo100talk · contribs · e@ 19:43, 13 July 2006 (UTC)

The answer is very basic. Over the course of time, people have taken a variety of risks, from walking under dead trees (could fall on you and crush you) to speeding down the highway stoned on pot while turning around the backseat to smack your misbehaving kids. Some of those things did indeed prove deadly to some people and those people are all dead. If you want to increase your chances of living a long time, do as few risky things as you can. Or, you could just decide you don't believe any thing can kill you and take your chances. Johntex\talk 19:54, 13 July 2006 (UTC)

Even more basic: what does "risky" mean? What do we mean by "dangerous?" I suspect that this is the OP's actual question. And in that case it's a matter of relative risk. For example, suppose we chose car-driving as our standard for common and well-known "acceptable risk." Then we can ask how dangerous all the other examples are in comparison to driving a car to work every day. --Wjbeaty 20:26, 13 July 2006 (UTC)day.

We are all dead. You just have to wait a little while. Add in heart disease and fist-hand smoke and I'll put pretty good money on something on that list getting you, too. Crazywolf

Many people do indeed die from said circumstances. We're all not dead because there are preventative measures that one undergoes. --Proficient 04:15, 14 July 2006 (UTC)

Two important factors here are accumulation and quantity/concentration. Heavy metals like lead accumulate in your body. A tiny bit won't kill you instantly (as you seem to suggest), but if you're exposed to tiny quantities regularly all your life then it will probably affect your health and shorten your life. About the quantity, that's a very common mistake. People hear that certain things are good or bad and then draw absurd conclusions like that one should not eat any fat or take shitloads of vitamin C. Any substance that is present in nature is something we evolved with and therefore probably healthy in the right quantity. A bit of arsenic or alcohol is healthy. To much (or too little) is bad. And way too much (for too long) is often deadly.

Germs are a special case because being exposed to them builds up resistance. So the shielding of kids from every sort of germ since the 50's or so caused an enormous rise in allergy. As for second hand smoke. If you mean from cars if you live in a city, yeah that's a serious health threat, comparable to first hand tobacco smoke.

If you wish to know the greatest risk to your life, you have to take into account not just the death toll, but also the age at which people die. About half a million people get killed by cars (directly) every year, at an average age of around 35 or 40. That's a loss of 20 million life years every year. I don't think even the big killer malaria is that deadly. DirkvdM 12:30, 14 July 2006 (UTC)

The Romans used to die early because their drinking water was heavily contaminated by lead from lead pipes etc. But they thought early deaths were normal and did not realise they were being poisoned.

I have had similar thoughts about Acrylamide, which is produced by frying, baking, and roasting. I have been trying to avoid it - a large proprtion of the daily dose comes from coffee. Boiled food or raw food (except olives, prunes, and prune juice) does not contain any. (I think it may be related to the browning of food, and I've been worried if currants, sultanas, raisins have it as I eat these everyday).

By the way, while I think of it, some months ago I added some content to the article on Acrylamide that balanced the complacent attitude of the 'author' (criticised for being so in the discussion). Then I found that the author had removed all my content and covered this up by saying the edit was just about a changed URL. The same author had had his request for promotion to admin status denied as their were suspicious circumstances regarding his nomination. I have avoided looking at the acrylamide article since because I'm too busy to article, and dont want to become involved in a 'war' or be upset by it.

ATP synthase enzymes are found in the prokaryotic plasma membrane and in mitochondria and chloroplasts. (1) What does this suggest about the evolutionary relationship of these eukaryotic organelles to prokaryotes? (2) How might the amino acid sequences of the ATP synthases from different sources support or refute your hypothesis?--Patchouli 17:33, 13 July 2006 (UTC)

Please take a short amount of time to familiarize yourself with the instructions at the top of the page. We're pleased to help out with most questions, but I'm afraid that we have to ask you to Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. TenOfAllTrades(talk) 17:56, 13 July 2006 (UTC)

I know the homework rule, but I posted it anyway for a good samaritan to answer. I don't mind if it goes unanswered.--Patchouli 18:01, 13 July 2006 (UTC)

The problem is that we don't want the reference desk to build a reputation as a place to bring homework questions. Hapless, helpless, or hopeless students would swamp the page with "Well, they answer homework questions sometimes, it's worth a shot" or worse "They ignored me yesterday, but I can repost today and try again" type posts. If you want us to go to the trouble of doing part of your homework, please try to at least paraphrase the question and (better yet) attempt your own answer rather than posting verbatim. TenOfAllTrades(talk) 18:17, 13 July 2006 (UTC)

(1) I surmise that ATP synthase enzymes moved from plasma membrane of prokaryotic cells (earlier) to the mitochondria and chloroplasts of eukaryotic cells (later) in the course of evolution. In other words, the mitochondria and chloroplasts of eukaryotic cells evolved from the plasma membranes of prokaryotic cells. (2) The similarity of amino acid sequences of ATP synthases from the plasma membrane of prokaryotic cells to those in the mitochondria and chloroplasts of eukaryotic cells could support this hypothesis.--Patchouli 18:39, 13 July 2006 (UTC)

Dinitrophenol (DNP) uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+. Explain how this causes weight loss.--Patchouli 17:38, 13 July 2006 (UTC)

By making the user waste time trying to get other people to do their homework? --Ginkgo100talk · contribs · e@ 19:27, 13 July 2006 (UTC)

You'd lose weight too if you had a leaky H+. --Kainaw(talk) 19:42, 13 July 2006 (UTC)

since we share in the work, does everyone on the reference desk get a share in your degree too? i could use another. Xcomradex 22:48, 13 July 2006 (UTC)

Three homework questions in a row, impressive. Try and think for yourself, though - what direction would H+ travel in if the inner membrane was "leaky", what would the effect of that be on the PMF? And what effect would that have? --Saintmocha 08:55, 14 July 2006 (UTC)

Then the H+ would diffuse into the cell. The proton-motive force wouldn't be there to perform work. But I don't see how the absence of a gradient can cause weight loss.--Patchouli 15:46, 14 July 2006 (UTC)

think about what was consumed to create that gradient, and what must used to recreate it. Xcomradex 01:47, 17 July 2006 (UTC)

I think ATP was used to create that gradient, and the higher usage of ATP to restore it causes weight loss. This is my wild guess.--Patchouli 03:16, 17 July 2006 (UTC)

exactly. given weight gain is due to energy input>energy output, you should now be able to see the answer. Xcomradex 02:49, 18 July 2006 (UTC)

(1) How do you suppose fermentation was first discovered? (2) Why did wine prove to be a more useful beverage, especially to a preindustrial culture, than the grape juice from which it was made?--Patchouli 17:42, 13 July 2006 (UTC)

Could you define your use of the term "useful beverage"? Dismas|(talk) 18:00, 13 July 2006 (UTC)

Grape juice doesn't tend to store well when you don't have good refridgeration--little creatures like all the sugar that is in it. When it is fermented, on the other hand, all the sugar has been turned into alcohol, which we humans like but the critters tend not to. Probably it was discovered when someone stored some sugary liquid in just the right way to end up with an intoxicating beverage. Digfarenough 18:04, 13 July 2006 (UTC)

Probably whenever 'the ancients' made grape juice, some of it ended up fermenting, and some people liked it, and figured out how to do it on purpose. --Bmk 18:24, 13 July 2006 (UTC)

Fermented beverages were discovered by accident, and the first one was probably mead (fermented honey and water) followed by beer (fermented malted barley). They were more useful than unfermented beverages because the alcohol is a preservative. In fact, no pathogenic organisms are able to survive in beer or stronger alcoholic beverages. See also History of beer and Wine#Early_history --Ginkgo100talk · contribs · e@ 19:21, 13 July 2006 (UTC)

I remember the story of an alcoholic who survived the bite of a venomous snake.--Patchouli 20:28, 13 July 2006 (UTC)

The most likely reason (without citation) for alcohol becoming a commodity is that it allows drunkeness, which many cultures regard as giving them a closer relationship with god. Many civilisations lick toads, eat fungi, consume plants for the explicit reason that they wish to become closer to their god(s) outside the normal reality. The most likely cause of consumption of alcohol is through the eating of decaying foodstuffs which was later encouraged and developed upon, though the evidence for this is lost in time. Apart from this, we have learned to enjoy the physical properties of fermenting organic fluids, even though we do not fully understant the processes at work. --russ 23:51, 13 July 2006 (UTC)

Alcohol is different from many other drugs in that the way it is produced is relatively complicated, which makes the question rather valid. The explanation I heard once is that some distant nomadic ancestor stored some grain somewhere for when he returned there, did so a few weeks later, hungry, finding the grain had gone bad, but eating it nevertheless because he was hungry and discovering it had a rather nice side-effect. This would have required just a little bit of alcohol, as is still the case peoples who haven't evolved with alcohol, like Indians and Aborigines. DirkvdM 12:41, 14 July 2006 (UTC)

For beer that should be obvious. But even wine takes some preparation. You can't just eat or smoke the grapes to get the desired effect. Even coffee is simpler (you can eat the beans). And opium is also simper I beleive (though I'm not sure, really). DirkvdM 19:12, 14 July 2006 (UTC)

Perhaps some forms of alcoholic beverages are complex, but others are incredibly simple. Apple cider turns into hard apple cider with no effort whatsoever, for example. And apple cider is just squished apples. StuRat 22:05, 14 July 2006 (UTC)

You'd first have to turn the apples or grapes into juice. Ok, that's fairly plausible. And then let it stand for long enough to go 'off' without going 'really off' (excuse my primitive language resulting from not precisely knowing what I'm talking about :) ). And that is a bit less obvious. My point is that all the other drugs can be detected through direct consumption. Once you know the drug is there you can start experimenting and find new (more pleasant) ways to digest it. But alcohol isn't there in the first place. You have to create it. And that has to happen by accident. It's not surprising that there are (at least) two peoples who never figured this out. DirkvdM 09:21, 15 July 2006 (UTC)

The alcohol production is self-limiting, as the alcohol eventually reaches a level that kills off all the bacteria. Even a caveman could manage to squish a few grapes. And don't worry, I'm used to you not knowing what you're talking about, by now. :-) StuRat 14:53, 15 July 2006 (UTC)

I can do better than that. Right now, I don't know what you are talking about. But that doesn't matter because you don't seem to know what I am talking about (how do I know that if I don't know what you are talking about, so what am I talking about? - Ok, I see your point ... ).

Anyway, the question is not whether he would be capable of doing it but why he would squash grapes and let the juice to rot if there are no obvious advantages. DirkvdM 08:40, 16 July 2006 (UTC)

How to manage and decontaminate the animal tissue culture wastes? Are these wastes hazardous in any way.

That depends. Biosafety level 1 culture wastes are unlikely to be harmful to humans, but may represent a hazard to some other organisms. Level 2 organisms generally represent a modest risk to humans. (I'm going to assume that you aren't dealing with Level 3 or 4 organisms, because you would have received proper training before they let you anywhere near that stuff.)

Your institution (hospital, university, or company) ought to have a policy on handling and disposing of biohazardous wastes; you should speak to your institution's biosafety officer for detailed instructions. Typically, liquid wastes are treated with bleach (sodium hypochlorite solution) or another disinfectant; after an appropriate time to allow the disinfectant to work these wastes can be poured down the sink. Solid waste is often autoclaved, then sent to regular landfill; incineration is sometimes used. (There are companies which specialize in the handling and disposal of biohazardous wastes.) TenOfAllTrades(talk) 19:37, 13 July 2006 (UTC)

no-one knows. the Neanderthals disappeared, but maybe that was because the invented contraceptives? dab(ᛏ) 21:20, 13 July 2006 (UTC)

Neanderthals had bigger brains, but size isn't evrything. A major disadvantage of neanderthals was that they were built more for strength (and to withstand the ice-age cold) and less for agility. Technology in those days often required agility. Neanderthals could only stab their spears, not trow them (not the right build), so when the forests started to disappear their techniques wer no longer useful. They might have copied the spears of the Cro Magnon man, but not used them. So it also depends on what you mean by 'advanced'. 'Adapted' is a more important word. DirkvdM 12:46, 14 July 2006 (UTC)

There may be something to the hypothesis that neanderthals had more physiological limits (larynx) to the way they could verbally communicate v. cro-magnons. Discovering a technology is one thing, but to keep improving on it for generations, there need to be some level of communication sophistication. So assuming that both species were technological equal at some point in time, the cro-magnons may have develop their technology further in time, thus gaining a definitive advantage.--JLdesAlpins 20:35, 14 July 2006 (UTC)

Of course Neanderthals could communicate (and verbally too, probably), but you don't need to communicate to develop a technique. Just trying for yourself and showing each other is enough. DirkvdM 09:25, 15 July 2006 (UTC)

I've been editing a few galaxy articles, and I was wondering if there's some kind of standard: If an event, such as two galaxies passing each other, really happened several million years ago, but due to light travel time, looks like it's happening right now, should it be written in the past tense, or the present tense? Should I propose a standard be created for light travel time? Either way, it should be uniform throughout wikipedia. --Bmk 21:11, 13 July 2006 (UTC)

The current observation is in present tense. The actual event is in past tense. For example, we are observing a bright light, from a star that exploded a billion years ago. --Zeizmic 21:20, 13 July 2006 (UTC)

Ohhh dear - this reminds me of a wonderful piece of gibberish by John Clarke about a sports event. it was discovered that the clock at the venue was 20 minutes fast, so rather than starting on time and being 20 minutes early, they decided to start 20 minutes late and be on time. Because of that the live radio commentary was replaced by a message saying that, since the event had already finished, live commentary would be transmitted as soon as it hadn't started yet. Grutness...wha? 03:20, 14 July 2006 (UTC)

There are also a lot of good (and not so good) books on the topic. Your local library or book store will have several or them. If you find those interesting, you might move on to [The Road to Reality] by Roger Penrose. It tries to be popularly accessible while not shying away from the fancy math. A tough slog, but a good book. --George 22:58, 13 July 2006 (UTC)

If you assume that Elementary particles have no structure, then there are no obvious constraints on which fundamental particles should exist. String theory is an attempt to explore the idea that each particle has a specific "structure" that can be thought of as a vibrational state of a "string". If a few simple assumptions about these hypothetical strings can be found to make verifiable predictions about particles, then the theory will have some pragmatic value. --JWSchmidt 23:00, 13 July 2006 (UTC)

Watch the 3 part show "Elegant Universe" or read the book. I found it very accessible and fun!--Sonjaaa 08:33, 14 July 2006 (UTC)

The reason is sulphur dioxide may trigger allergic reactions and aggrevate aesthmatic reactions in some people. In the EU this statement is illegal, as ingredients listings in alcoholic beverages are forbidden by law, however many supermarket chains put this information on regardless as a check against people having a reaction and sueing them. It should be noted that sulphur dioxide is a necessary component in the manufacture of quality, stable wine and is allowed in limited amounts even in wines labelled as 'organic' (i.e. without the use of chemicals). This is because it is very difficult to produce wine of any real quality without it. The SO2 is used not as a preservative, as the article on sulphur dioxide states, but as a way of preventing wine from becoming unstable and becoming bacterially infected, losing colour, becoming fizzy, or developing many other faults which would render it unpalatable and unsaleable --russ 23:42, 13 July 2006 (UTC)

Isn't "preventing wine from becoming unstable and becoming bacterially infected" exactly what a "preservative" is supposed to do ? StuRat 00:07, 14 July 2006 (UTC)

Why on earth is is illegal to print ingredients on alcoholic products in the EU?? --Bmk 00:33, 14 July 2006 (UTC)

They are afraid California will make a copy that's just as good for half the price, using Mexican immigrants as workers. StuRat 02:25, 14 July 2006 (UTC)

Is it really true that listing ingredients in alcoholic products is illegal?? I always assumed that these were one of the few products where not listing ingredients is legal, and that manufactures take advantage of that leniency to inhibit competition. Alf Boggis 17:16, 14 July 2006 (UTC)

I think listing ingredients is not compulsory, and manufacturers are happy for it to stay that way: for example, a popular British brand of cider says on the label "Made with selected cider apples". Note with, not from, which makes me suspect that apples are not the principal ingredient, and that a list of ingredients, ordered in decreasing amounts as is customary, would run something like "water, glucose syrup, malic acid, colouring, flavouring, apples, carbon dioxide, acesulfame, sulphur dioxide". Perhaps I'm just being cynical. Malcolm Farmer 17:12, 16 July 2006 (UTC)

I'm not 100% certain whether it's illegal or just optional to list ingredients on wine, but I'm pretty sure that the 'contains sulphites' label on alcoholic drinks is actually compulsory under EU law, precisely because of the possibility of allergic reactions - Directive 2003/89/EC, in the unlikely event that you're interested ;o) Nicola79 16:53, 19 July 2006 (UTC)

I left some freshly made meatloaf out last night for about four or five hours at 75 F. Is it safe to eat? It's been in the fridge since then. Should I microwave it for a while to make it safer? Would that help much? grendel|khan 23:48, 13 July 2006 (UTC)

The safe recommendation is to toss it out, but cooking the hell out of it should certainly make it somewhat safer. If it smells bad or has changed colors, I'd toss it. Also, if it was left uncovered or exposed to insects (flying or crawling) I'd toss it. StuRat 00:03, 14 July 2006 (UTC)

Oh, it was uncovered. Darn, and it was such a delicious homemade meatloaf. Doesn't smell funny or anything. I thought that bringing the temperature to 212 degrees sterilized things; is it not the bacteria content that would be the danger? grendel|khan 00:36, 14 July 2006 (UTC)

Well, for one, I don't think that would do much against endospore forming bacteria, on second thought, 212 degrees what? degrees C, degrees F, or just plain old K? hopefully not K, I don't think freezing bacteria does much ;-)152.163.100.74 01:06, 14 July 2006 (UTC)

Speaking as a vegetarian (lol) I'd say it's probably OK. Thoroughly reheating it should kill any microbes, and IMO that amount of time wouldn't be enough to cause the meat to decay (the other reason it's not healthy to eat food that's been sitting out). I frequently leave food sitting out overnite, not meat of course, but it's always OK. I'd just be cautious about anything that can't be heated, like potato salad, or something that can actually rot overnight, like milk or food that's already several days old. And don't worry, this answer isn't a cover for 'one less meat eater', lol. And BTW I feed my dog raw meat, and I frequently leave it out overnight to defrost it, up to 12 hours, it's room temp when I'm done, and she never gets sick.--Anchoress 01:09, 14 July 2006 (UTC)

I reckon it would probably be OK, particularly if it was cooling during the 4-5 hours that you left it out. Microwaving would probably help. BenC7 01:15, 14 July 2006 (UTC)

When you purchased that meat at your grocers, it was covered in varrious kinds of bacteria. You then cooked it to an internal temperature which (hopefully) killed most, but not all of that bacteria. So what kind of bacteria was it? In ground meat, the biggest bacterial enemy is a certain strain of E. coli, which innoculates the meat when it comes into contact with fecal matter (pretty common) and gets mixed in by the grinding process. So some of that bacteria was left in the meat even after cooking, it's a fact of life. The moment the meat started cooling down, that bacteria started growing again. Now, with bacteria like salmonella sp. and listeria sp., this is not a big deal, because they grow very slowly. escherichia sp., however, grows very rapidly. So in the five hours that the meat sat out, this pathogenic bacteria could have gone through, at most, 30 generations (some strains have 20-minute doubling-times). To put that in perspective, that's 2^30 times as many bacteria as you started with. If you got a meatloaf with just 1000 bacteria in it (a ridiculously low number) and killed 99.9% of it by cooking, you could still have more than a billion bacteria after 30 generations under ideal conditions. Even if you cook that meat again, killing 99.9% of the bacteria in it, you would still have a more than ample pathogenic load to make you sick. I don't think I would eat it. By the way, where did you get 212°? Bacteria (in the real world, there are some that can overcome this temperature barrier, but...) 121°C is sufficient to kill everything (that is the temperature an autoclave reaches). Also, the comments given by the vegetarian above, though undoubtedly in agreement with his or her observations, may be hazardous. Don't leave your meat out overnight (defrost it in the refrigerator), and don't be fooled into thinking that the process of "rotting" or "decay" in meat or milk or any foodstuff is anything other than bacteria in action. (perhaps you were thinking of rancidity Anchoress?).Tuckerekcut 02:24, 14 July 2006 (UTC), MS Microbiology.

Hi Tuckercut, point taken. I will, however, continue to defrost my meat outside, I've done it for 6 years with no sickness, no reason to change. And as for the milk thing, I don't think we're in disagreement, perhaps I didn't communicate clearly. There are two things at work, microbe infestation, which can make you sick, and food that is rotten, which can make you sick. Even completely sterile rotten food can make you sick. The food may have become rotten through the work of microbes, but if you kill the microbes the food is still rotten. That's what I mean by milk, etc. Some things, like cheese, fruit, etc, can survive room temperature exposure for a long time before rotting. Other things, like milk, will rot very quickly after reaching room temperature. Is it because of microbes? News to me, but I don't doubt you. Would the food still make you sick after killing all the microbes? Yes. That's what I'm trying to say. :-)--Anchoress 03:53, 14 July 2006 (UTC)

212 degrees Fahrenheit is the boiling point of water. Therefore, any food with a high water content, like meat loaf, can only be heated to that point. To heat it beyond that temp would drive out all the moisture and burn the meatloaf. StuRat 03:44, 14 July 2006 (UTC)

Not instantly. And the thing with microwaves is that they work pretty instant. Loads of heat in a short time is what they're good at. DirkvdM 13:01, 14 July 2006 (UTC)

Microwaves only rapidly heat small objects. They would take forever to cook a 20 pound frozen turkey (and it would be inedible when done). StuRat 22:12, 14 July 2006 (UTC)

Another thing that would help would be to cut off the exposed outer layers. The interior should have had less bacterial exposure. StuRat 02:31, 14 July 2006 (UTC)

The preceeding comment is unfortunately incorrect (sorry StuRat!). The bacteria coming in from outside is inconsequential over this timeframe. The nasty bacteria is already in the meatloaf. Cutting off the outside will not decrease your chances of ingesting pathogenic bacteria.Tuckerekcut 02:48, 14 July 2006 (UTC)

I disagree. The cooking process should have killed off any bacteria in the interior. StuRat 03:39, 14 July 2006 (UTC)

[inserted here to simplify flow of argument] The cooking process, specifically increasing the interior temperature of the meatloaf to about 75°C, would not have killed all the bacteria in the meatloaf. To do that, one would have to raise the temperature to at least 121°C (~250°F) for at least a few minutes, which would result in a dish that would not be, as the question asker stated, "...a delicious homemade meatloaf," but, more likely, a perfecly functional doorstop. The cooking process really just kills enough of the organisms to be safe to eat, I would guess about 999 out of every 1000, but that still leaves a lot of viable organisms to act as progenitors. As an undergrad, I remember that one of my professors worked with a bacteria (Archaea, actually) sampled from hot springs in Italy, that grew best at 75°C. And the infamous T. aquaticus, from which scientists get Taq polymerase, grows in the boiling hotsprings of Yellowstone National Park, and is perfectly happy for small stints at 95°C.Tuckerekcut 17:23, 14 July 2006 (UTC)

It depends on the cut of meat. For whole cuts, most of the bacteria were on the surface to begin with. Cooking the meat kills everything, and cutting off the outer layers or cooking again will make it fairly safe. For ground meat, the bacteria are mixed in with the meat, and cooking only kills most of them -- the interior of a meatloaf or a burger patty doesn't get anywhere near as hot as the surface of a grilled steak. Once the temperature drops to a safe level, the surviving bacteria start growing again, and this growth is throughout the meat. --Serie 21:44, 14 July 2006 (UTC)

Toss the meatloaf. Remember to refrigerate it next time. Food poisoning can result both from live bacteria and from toxins produced by those bacteria, even if you've killed the bacteria (by cooking) after they've produced the toxin. Meat dishes are often contaminated by Staphylococcus aureus, which produces a heat-stable toxin. Enteropathogenic E. Coli, another frequent contaminent of meat dishes, also produces a heat-stable toxin (as well as various heat-sensitive toxins). In general, if you get sick 4 to 6 hours after eating, it's due to preformed toxin; if you get sick 12 or more hours after eating, it's due to the bacteria proper. - Nunh-huh 08:16, 14 July 2006 (UTC)

My criterium has always been the smell. If it doesn't stink it's ok. And if meat stinks a little and has a slimy surface I rinse it and cook it extra long. I've never had food poisoning. Then again, I have always done this, so I've built up resistance. DirkvdM 13:01, 14 July 2006 (UTC)

Definitely don't eat the meatloaf without heating it ... I would be suspicious of it even if you did reheat it as much as possible. Also, it will not be a tasty meatloaf any longer if you overcook it that much. So, just toss it and chalk it up as a lesson learned for next time. --Ginkgo100talk · contribs · e@ 15:18, 14 July 2006 (UTC)

I've tossed the meatloaf because, on further consideration, eating it would fail the "emergency room test", meaning that I'd feel real stupid waking up in the ER and explaining that, well, the meatloaf was tasty and some guys on the Wikipedia reference desk said that it might be okay if I reheated it heavily. I find that this keeps me out of all sorts of trouble. grendel|khan 00:12, 15 July 2006 (UTC)